Over the course of the last two centuries the developed world has become increasingly industrialised. While this has brought unprecedented rates of technological advancement, it has also been responsible for some drastic changes in our environment, particularly the quality of air. These pollutants often arise from the burning of fossil fuels in power stations and vehicles, manufacturing products, and other industrial processes. Furthermore, pollutants can also enter the atmosphere from natural sources including from volcanic eruptions, dust storms, forest and grassland fires, living vegetation, and sea spray.
While the causes of climate change are often contested, it is widely agreed that pollutants such as ozone, nitrogen dioxide, sulphur dioxide, and particulates—often broken down into coarse particulate matter less than 10 microns in diameter (commonly denoted as PM10) and fine particulate matter less than 2.5 microns in diameter (commonly denoted as PM2.5)—are not desirable for a number of reasons. Air pollution has been linked with disease, death to humans, damage to other animals and plant life including food crops, and damage to both the natural and built environments.
Environmental monitoring, particularly air quality monitoring, has therefore assumed increased importance in recent years. Air monitoring systems are highly important for monitoring the level of various pollutants within the air, particularly around industrialised areas or areas that typically have a lot of vehicular traffic that may be outputting undesirable substances into the surrounding air.
Conventional air monitoring systems contain a large amount of equipment for monitoring the air quality of the surroundings. For example, they typically house a number of different instruments for measuring air quality such as sample probes, filters, gas conditioning systems, a number of gas analysers that are used to check for the presence of different pollutants such as NO2 and SO2, and particulate matter samplers used to monitor for PM10 and PM2.5 particulates. These systems are typically installed on industrial sites and proximate to roads in order to monitor the quality of the air in areas that are of concern.
Conventional air monitoring systems are usually large, self-contained units that resemble storage containers. The size of these systems makes them difficult to transport and install. These conventional systems are also typically very expensive, rendering it uneconomic to install large quantities of them in order to cover a wider area.
There are microsensor systems on the market that can provide an indication of air quality that are a fraction of the size of the above-mentioned systems. However, the Applicant has appreciated that these microsensor systems are typically not sufficiently accurate and reliable for use in environmental monitoring, where accurate and reliable measurements are of paramount importance. In particular the Applicant has appreciated that existing smaller scale microsensor based systems are typically very sensitive to changes in their operating temperature as well as the temperature and relative humidity of the air samples taken.